Ocean Migrations of Pacific Salmon

Abstract

Sockeye salmon (Oncorhynchus nerka), pink salmon (O. gorbuscha), and chum salmon (O. keta) commonly return to their places of origin from distant high-seas areas. Maturing fish closely associated at high-seas localities travel in many different directions to their respective destinations. They also travel from many different high-seas localities to a common coastal area. Prior to their return to inshore waters, pink salmon perform ocean journeys which are associated with changes in temperature and which do not necessarily represent a direct approach to a spawning area. The ocean journeys of both juvenile and maturing salmon are largely independent of currents. Homing is not thought to be commonly accomplished by random or near-random ocean travel or by extensive searching of coastlines. It is suggested that ability to set a compass course, using a celestial feature, is insufficient to account for the indicated performance and that some form of bico-ordinate navigation may be required.